I have a cousin who was agonizing over marrying a woman because her mom was overweight. He did end up marrying her. His own parents are slim. Well, as it turns out, his thin dad died at 70 of a terrible neurological disease (rare enough I won’t specify). His thin mom is doing well, but so is his wife’s overweight mom.
The kicker is he struggles with his weight - his wife - the daughter of the overweight lady - has much less difficulty with her weight (not svelte by DCUM standards, but OK in terms of medical guidelines).
So you never know how it will turn out!