Children are extremely impressionable, what they see as youngsters stays with them for ever. If you teach a child a rose is a tulip. He’ll believe it till he goes to school and is told otherwise (most likely with jeers from his peers).
Children are like chalkboards in that sense. The first time you write on a new chalkboard it’s fresh and the lines are clear, the impression is crisp and clear. As time goes on and the chalkboard is erased the board gets greyer and no impression is as crisp as it was the first time.
Also the impression is never completely erased, it’s silhouette is still there and the harder the impression was the clearer its silhouette remains.
This is what it’s like with us, hence be careful what you say around your kids and what message you’re sending them as kids cause it stays with them for a long long time.