Yes and no.
For example, my mother is one of 6 children, all growing up in the same household. Mama and Papa were both obese.
Of the 6, four are obese, and 2 are very slender.
The slender ones grew up in the same lifestyle, inheriting the same viewpoints on food as their siblings.
Most likely, either they simply gravitated towards a healthier lifestyle as adults (as we do - some people like golf, others like horses, and some like motorsport, etc), or else there's a genetic component to all 6 kids' weights, with the genetic tendency towards obesity obviously being dominant, but a genetic tendency towards slenderness not exactly being non-existent.
I'm gonna lean on genetics a little here, much as I said lifestyle trumps it earlier, in that my mother was one of the obese. Nana was obese, mother is obese, I am obese. I do believe that I find it much harder to lose weight and stay a healthy weight than certain other relatives who do not have such a genetic tendency.
So basically, lifestyle will always trump a genetic "tendency". But for some people it's easier to maintain that lifestyle than for other people.
Deb, in New Zealand