I disagree - Sasha and Alena are both pretty tiny for their ages. A lot of that is genetic, but we also know how fixated Eteri's training methods are on low weight = quick rotation speed.
Alena might be short but she looks pretty mature apart from her height. Sasha does seem naturally skinny but she's built up so much muscle that I wouldn't call her tiny either. I don't think she's depending on low weight to get those quads in since muscle is much denser than fat.