children will probably grow different too: shorter, more muscular, maybe stronger bones
Or they could be born premature due to gravity exerting enough force when a pregnant woman stands up to "pull" them out. Or perhaps they wouldn't be born at all. Or perhaps they would be born and many would die due to an inability to breathe properly. Or they could never progress past the crawling stage. Or or or or.
Genetics explains why you look like your father, and if you don't, why you should.