I think the surnames thing is partly about signalling ethnic identity (northern European/white/WASPs). You don't often see people adopting surnames that suggest other types of heritage! "Feminine-sounding" names ending in "a" are common among both Hispanic families (Sofia, Carmila etc.) and African American families (Aliya, Kayla etc.), and I think at the subconscious level, some white families need the need to sound very "different" from this. Not criticizing, everyone has the right to their own group identity. Just commenting
I don't really agree with this. It doesn't really ring true from my observations.
Hispanic families tend to give children Spanish names, and also Anglo names that are slightly unfashionable (Nicole, Melanie, Amy, Dylan and Kevin..) In the case of girls, the Spanish-language names tend to end with an A, though there are names like Aracely, Jazleen, Jazmin, Guadalupe, Daisy, and Monserrat that are popular but don't fit this pattern. By the same token, Sophia, Olivia, Emilia/Amelia, Ava, Mia, Emma, Isabella, are top ten names for girls in general, not confined to Hispanic baby girls by any means, though European-origin parents tend to avoid names like Yaritza, Lizbet, or Yajaira that are easily identified as Hispanic.
Across the board - including boys with obvious Eastern European family names (mainly Polish where I am) - boys are getting the surnamey names in the MC area where I live, with the exception of Hispanic and some Jewish boys (there are several strands of Jewish culture though, and this is reflected in names). Caucasian (of all stripes) and African American boys named Mason, Carter, Sawyer, Sterling, Jackson, Harrison, Archer, Spencer, Davis, Meyer, Miller, etc, abound, along with more traditional names from both Judeo-Christian and Islamic heritage. It's a huge change from a generation ago when a name like Jackson was most unusual.
Many girls rejoice in names like Kinsley, McKenna, Skylar, Paisley, Everly/Everleigh, Avery, and Brooklyn, but older names like Grace, Emily, Abigail, Elizabeth, Chloe, and all the A-ending names are still there in big numbers. Then there are newer 'old' names reflecting the trend for granny chic in the UK - Evelyn, Vivian, Charlotte, Cora and Nora are all hot where I am. I suspect this is the Downton effect.
There are some racial divides: Octavia tends to be an African American choice rather than Caucasian.