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Name: JC
Status: Student
Grade:  9-12
Location: AL
Country: United States
Date: August 2005

When did science actually find out about the male determining the sex of the child?


May be of help.

Yes, normally the Y chromosome from the male will dictate a male child. However, it is more important to understand the sry gene that actually determines maleness. Females carry this gene too. There are males who are XX and have no Y chromosome; and their are females with Y chromosomes. For the most part males determine the sex of the individual, but it is not that simple in every case.

What year? About 50 years ago when it was shown conclusively, but it was guessed about over 150 years ago when Mendel did his work and when Morgan (circa 1905) worked with fruit flies.

Steve Sample

The Y chromosome was discovered in fruit flies by Thomas Hunt Morgan circa 1910. Up until 1956, the number of chromosomes in humans was thought to be 48, but improved methods of observing chromosomes microscopically revealed that there were actually only 46 chromosomes in humans. I wasn't able to determine the exact year in which human females carry 2 X xhromosomes and males only one plus a Y chromosome.

Ron Baker, Ph.D

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