Alyona's 19 yrs old, got a pretty good game, shes mainly an aggressive baseliner and hits the ball pretty hard but shes inconsistent and streaky. Her best results are winning 2 25K's.
Katerina's her younger sister, i dont know that much about her, shes a junior player and i think shes about 17. Her results seem ok so far on the pro tour.
I think they've got another sister, Valeria, but she isnt nearly as good as either of them.