Their adoptive parents, surrogates. Mostly due to the fact their environment and their traits are picked up upon.
It depends what age you adopt them. The younger they are the more likely they'll be influenced by you
Nature vs. Nurture.
Some habits will be from the adoptive family some traits from the biological family.
nature verses nurture id say a bit of both swaying slightly on the side of nature
both, there are somethings they inherited from there bio-parents but most behavior is learned. monkey see monkey do kind of thing
I think the influence such as morals, rules, social stuff etch become apart of that child , and to a certin extent so do their attitudes and habits.
But personality and characteristics are from biological parents. But it all depends on the cilds upbringing and influence.
Who is to say? Every child has the oportunity to develop into a truly unique person. It might also be that they are not becoming like either parents.