Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

It is not only that an X
chromosome a woman is from
father, it is certain. woman has
an X from her father and
other X chromosome from
mother.

In men however X chromosome
comes always his mother and the
chromosome is always from
father.