Muscular veins run in my family too. Even at 124 lbs, people said I looked buff because of them (in my arms), but I've never lifted a weight in my life. If you have what I had, you raise your arms above your head, and they disappear, but you lower them, and they puff up.

Happily after 2.5 months on HRT, and gaining weight to 139 lbs, my arm veins are not noticeable anymore. I looked at my hands last week and for the first time said "Wow" as my hands finally look softer (though you can still see the veins at times, so there is progress to go). I think a lot of this is because my skin seems rounder now in all the places it used to be muscularly/boney.
(An AA is included in my HRT regimen).