sentences:  The other effect is an indirect effect in relation to mutations on the X chromosome which are passed to daughters who are then at risk for having sons with X-linked diseases.In 1912, Wilhelm Weinberg, a German physician, was the first person to hypothesize that non-inherited cases of achondroplasia could be more common in last-born children than in children born earlier to the same set of parents.Weinberg "made no distinction between paternal age, maternal age and birth order" in his hypothesis.