Yes, being poor or even simply growing up poor can contribute to keeping you poor by restricting your lifestyle choices.
And I don't know how many times we can repeat that we're talking about averages here - the prospectives of *most* poorer kids versus the prospectives of *most* wealthy kids. We are well-aware that with a combination of skills, education, a more-than-average natural inclination to overcome difficulties, good health, quite a bit of luck, etc, some poor kids are able to do something with themselves. Depends on the area they're living too.
There's no reason to keep bringing it up, nobody said "all kids born poor will die poor". We're saying that, in general, kids born in poor families have signficantly less changes of "making it" than kids born in more wealthy families(or even countries). It's statistics of big numbers. Exceptions to the rule exist. We're a programmers forum's for crying out loud, I think we all understand patterns, and that something does not have to be black-or-white in order to follow a general trend. I really think some people here understand perfectly that we're talking about general patterns and trends that always have exceptions, and that a 1-in-20 counterexample isn't strong evidence that those trends don't exist, but they do it anyway.