Why do some look like a bulldog after sixty and some don't?

Genetics, mostly. Some aging is due to weathering.

Weight and weight fluctuation. Physical activity levels. Smoking or not. Drinking or not. And a bit of caring for skin when outside, although getting enough Vitamin D from the sun helps keep one young.

And of course any major illness can make you look older too.

Sun damage and genetics. I think sun worshipers have it the worst.
Poor nutrition as well, and lack of exercise.

It’s the younger ones I feel sorry for, those who resemble a bulldog licking piss off a thistle.
Bless, for them sorry buggers genetics is a four letter word.

I’d normally say genetics but in these times I’d rank weight fluctuations, sun exposure and drinking/smoking show wear and tear.

Sun damage. simple.