How is it possible for a child to end up with a diiferent genotype or phenotype than either of their parents?

Tall parents can have a short child, short parents can have a tall child , and two parents of the same height may have a child in between? 

It is possible for a child to end up with a different genotype or phenotype than either of their parents because children get one allele from each parent. For example, if both parents were heterozygous for a trait, the child may get the recessive allele from each parent and end up with the homozygous recessive genotype and the recessive trait.