I kind of doubt that declawing has made your cat aggressive. I know a number of declawed cats and they all seem not to even know. They paw away at the couch or a speaker grille like they have claws.

Male cats tend to be larger than the females from the same litter (there’s a lot of genetic variables) and the males get jowly as they get older so even if they are the same size as a female, you can tell the male just by his face.

Personality has a lot to do with upbringing, genetics and a lot of other variables just like human children.