There are also, according to the Baby Name Wizard, cycles. Names of your mother's generation (for me, Linda, Sue, Debby, Barbara) all sound like your mother-in-law's name, and they make you think of a 50-year-old woman. Names of your grandmother's generation (for me, Mary, Betty, Dorothy, Shirley) all sound like old lady names.
But you probably never knew your great-grandmother, or at least very little, and not many other people of your great-grandmother's generation. You may have heard stories about her, and stories from when she was a little girl. You may romanticize her generation, and earlier than that. So the names of that generation and earlier (for me, Ruth, Virginia, Elizabeth, Evelyn) don't have as much baggage to them.
Of course, there are names that we like and names that we don't like from those generations, because there are other trends that drive us. For instance, there's a current trend towards boys' names ending in -n. Just like Carotte said that in France there's a trend towards boys' names ending in -o.
Girls' names with two syllables (or sometimes three) ending with -a are really popular right now. Ava, Sophia, Olivia, etc. Soft letters like s, ph, l, and v. Lots of k's and m's, too. But not as many d's, and generally flowing names. So some women may be choosing old-fashioned, uncommon names, and then finding that Julia, or Sylvia, turns out to have three others of her name in her preschool class, because the other women are of the same generation and they are all being affected by language the same way such that they are also looking for those soft consonants and flowing names with the -a ending.