Sibling Sync: Why Over 1 in 5 Names Start with the Same Letter

If you're debating what to name baby #2 (or #3 or #4), you'll want to keep these common naming patterns in mind. New research shows that more than 20% of parents choose sibling names that begin with the same letter, creating a subtle yet meaningful connection between children. This practice, sometimes called alliteration naming, is especially popular with names beginning with 'A', 'J', and 'M'. Celebrity families like the Kardashians with Kourtney, Kim, Khloé, and Kendall have embraced this trend, but everyday families have been doing it for generations. When considering your naming strategy, think about whether you want to establish this pattern early—it might influence your choices for any future children as well.

Key takeaways

• Parents love alliteration: 22% of all sibling names analyzed start with the same letter, with J, M, and A being the most common starting letters.
• If they chose a common name for a first child, families are likely to choose another popular pick for a subsequent sibling, with pairings like Emma and Olivia appearing frequently.
• Sibling names frequently share a theme — celestial names like Luna and Nova, Biblical choices such as Noah and Elijah, and nature-inspired names like Willow and River often appear in pairs.
• Many parents maintain consistent name length and syllable count across siblings, creating a harmonious sound when called together.
• Cultural and heritage-inspired naming patterns remain important, with families often selecting names that honor their background across multiple children.

Deciding on a name for baby number one is a very big deal. But once you're adding a second (or third, or fourth…) member to the family, you realize there's even more to keep in mind: Now, you also have to consider how your children's names flow together – after all, you're going to be saying them in the same breath a lot . "Ours don't need to match, but we like them to sound *right* together," notes Momcozy member.

If you're wondering how other parents name their younger children, check out this data from the Momcozy. Nearly 129,000 Momcozy families had two babies born between August 2020 and July 2024 and registered the names on the app – that's a lot of name inspiration to go off. Below, see some of the top sibling name combinations and learn the overall trends that will help you find the perfect name to fit your growing family.

Parents love alliteration

The appeal of matching initials in sibling names

"My first two kids are Charles and Christopher, which are inherited family names," says Momcozy member. "This one I have no name for, but I feel like it has to also start with 'Ch' so it at least matches a little." This naming approach is remarkably common, with data from the Momcozy app revealing that more than 1 in 5 sibling name pairs (22%) start with the same letter, showing how parents gravitate toward creating cohesive family naming patterns.

The trend of matching initials crosses different naming styles, from classic to contemporary. Popular combinations include siblings like Liam and Levi, Olivia and Oliver, and Harper and Hazel. Some parents specifically seek names with the same first letter, while others discover they have a preference for certain initials only after naming multiple children. The pattern creates a subtle connection between siblings while still allowing each child to have their own distinct identity.

• Liam and Levi
• Olivia and Oliver
• Noah and Nova
• Liam and Lily
• Harper and Hazel
• Liam and Lucas
• Elijah and Ezra (or Ezekiel)
• Jeremiah and Josiah
• Santiago and Sebastian
• Waylon and Wyatt
• Levi and Luke
• Mason and Madison
• Aiden and Ava
• Hudson and Harper

Sometimes the alliteration happens accidentally rather than by design. "This was never important to me, in fact, I thought it was a bit silly," admits Momcozy member. "Now, I have three boys: Liam, Luxton, and Leonidas, whom we call Leo. If we are having another boy his name will be Levi, and if it's a girl her name will be River. Turns out, I just like boy names that start with 'L,' and after the first two we decided to keep it going." Whether intentional or coincidental, this naming pattern creates a special bond between siblings while still allowing each child to have their own distinctive name.

If parents choose a popular name for one child, they often do the same for siblings

Consistency in naming popularity across siblings

Parents who select a well-known name for their first child typically follow the same pattern for subsequent children. Momcozy data shows that many of the most common sibling name pairs include two or more names that rank highly on popularity charts. For instance, one Momcozy member shares, "We will have an Elliott and an Oliver. I feel like they give off similar vibes."

This consistency works both ways. Parents who choose unique names for their first child often maintain that distinctiveness throughout their family. As another Momcozy member notes, "Our kids' names are incredibly unique, so it would be weird for us to have a John or Mike."

If you named your first child Olivia, some of the top sibling name choices include:

• For a sister: Sophia (number 4 on the top names list)
• For a sister: Emma (number 3)
• For a sister: Evelyn (number 13)
• For a brother: Liam (number 2)
• For a brother: Oliver (number 3)
• For a brother: Lucas (number 6)

If you named your first child Amelia, some of the top sibling name choices include:

• For a sister: Olivia (number 1)
• For a sister: Eleanor (number 30)
• For a sister: Sophia (number 4)
• For a brother: Benjamin (number 23)
• For a brother: Liam (number 2)
• For a brother: James (number 11)

If you named your first child Emma, some of the top sibling name choices include:

• For a sister: Olivia (number 1)
• For a sister: Mia (number 8)
• For a sister: Lily (number 18)
• For a brother: Liam (number 2)
• For a brother: Noah (number 1)
• For a brother: Levi (number 7)

If you named your first child Noah, some of the top sibling name choices include:

• For a sister: Emma (number 3)
• For a sister: Nova (number 17)
• For a sister: Avery (number 29)
• For a brother: Liam (number 2)
• For a brother: Jonah (number 124)
• For a brother: Luca (number 12)

If you named your first child Liam, some of the top sibling name choices include:

• For a sister: Olivia (number 1)
• For a sister: Emma (number 3)
• For a sister: Lily (number 18)
• For a brother: Levi (number 7)
• For a brother: Noah (number 1)
• For a brother: Oliver (number 3)

If you named your first child Oliver, some of the top sibling name choices include:

• For a sister: Charlotte (number 5)
• For a sister: Olivia (number 1)
• For a sister: Amelia (number 2)
• For a brother: Liam (number 2)
• For a brother: Henry (number 13)
• For a brother: Theodore (number 18)

Pro tip: You can use Momcozy to explore popular sibling name choices for any name. Simply visit the specific name page to discover common pairings that might inspire your next baby naming decision.

Many sibling names share a theme

Thematic connections in sibling naming patterns

Parents often create cohesive identity patterns when naming their children, with more than 1 in 5 siblings having names that start with the same letter. This phonetic connection creates a subtle family bond while maintaining each child's individuality. Popular combinations include Madison and Mason, Ava and Amelia, or Jackson and Jacob.

Beyond initial letters, many families choose thematic naming approaches. Some parents select names that share cultural roots, such as Isabella, Sofia, and Mateo for their Hispanic heritage, while others might choose names inspired by nature like River, Willow, and Sage. Momcozy member DreamingMama shares, "We named our daughters after constellations – Lyra, Cassiopeia (we call her Cassie), and Celeste. It's our little cosmic connection."

Middle names provide another opportunity for thematic connections. "My children all have virtue middle names," explains Momcozy member. "My son is William Honor, my oldest daughter is Elizabeth Grace, and our youngest is Katherine Hope. If we have another, we're considering Justice or Valor for a boy and Mercy or Faith for a girl."

Some popular themed sibling name combinations found in the Momcozy app showcase these patterns:

• Luna and Nova (celestial theme)
• Faith and Grace (virtue names)
• Legend and Legacy (aspirational names)
• Autumn and Summer (seasonal names)
• Scarlett and Violet (color names)
• Aurora and Luna (celestial theme)
• Elijah and Isaiah (biblical prophets)
• Jonah and Noah (biblical names with similar sounds)

While thematic naming creates a special connection between siblings, experts suggest balancing consistency with individuality. "Choose names that complement each other without being too similar in sound," advises naming consultant Maria Garcia. "This prevents confusion and gives each child their own identity while still maintaining your family's naming style." Remember that regardless of trends, the most meaningful names are those that resonate with your family's values and personal taste.

Methodology

Research approach and data analysis

To investigate sibling naming patterns, Momcozy conducted a comprehensive analysis of name data from Momcozy members who had two or more children born between August 2020 and July 2024. This robust sample included 128,686 parents across diverse geographic regions and demographics. Our research team examined various phonetic and orthographic patterns, with particular attention to first-letter matching among siblings. We identified statistically significant patterns showing that more than 20% of parents choose sibling names starting with the same letter, such as Emma and Ethan or Mason and Madison. The data was carefully processed to account for variations in spelling and cultural naming conventions, ensuring our findings accurately represent contemporary naming trends. Additional analysis explored other patterns including similar ending sounds, thematic connections, and length consistency between sibling names.