Maybe they just like classier boy names than they do girl names. I know a lot of sibsets like that. Valeriano's really cool, I think.
Davide is nice.
Mayra isn't THAT bad imo, at least it has two consonants next to each other, but it does throw it off balance.
Reminds me heavily of a sibset I know:
Grayson,
Joshua, and
Clara "
Claire," in the upwards progression in quality. I had a discussion with the father though, and apparently that's purely coincidental.