If a child is 10yrs. old, and then has a new brother/sister, the birth order is now changed.?

Depending on the child and circumstances, they will either be excited to have a new little sibling or resentful.

I'm not sure I understand what your question is. Are you asking that since the 10 year old would no longer be an only child, but the older child, that his/her personality will change?

If so, then that's not at all true. The personalities the older, middle, or the youngest are *supposed* to have are much like horoscopes. Not really true, but fun to believe.

I am the oldest child, and I don't act like it at all! My brother ( who would technically be the baby of the family) is much more dependent and "scholarly" than I am. Plus, I always joke that I am the favorite (usually reserved for the youngest, if you believe in all that) because I gave our parents their first grandchild...LOL

They might become more gentle, because you can't rough house with a baby.

They might also feel a bit neglected because the new baby needs a LOT of attention, but they will realize that Mommy and Daddy love them as much as always.