Describe heredity and evolution in humans?
Heredity is the passing of traits and information from Parents to their offspring.
A division of Biology called Genetics is the study of heredity.
Evolution is the changing of genetic material in a population over time. Many people jump to the conclusion that "Evolution means humans came from monkeys." This is a very narrow view of the definition. Evolution really states that the genetics of a population change over time, and that these changes, given enough time, can result in changed traits in the population.
These are really two separate questions which are quite unrelated. In response to the first question I will just say that humans evolved from some kind of apes over a period of 5 to 10 million years.
Coming to the second question, I will explain this in more detail. The sex of a baby is determined by the kind of male sperm that combines with a female egg to start the process of development and growth of a baby. Humans have two type of chromosomes X chromosomes and Y chromosomes. The female egg always contains an X chromosomes, but the male sperm can have either of X or Y chromosomes. The baby will be a boy when the male sperm fertilizing with female egg has a Y chromosome, and a girl when it has an X chromosome.