DNA

DNA testing is growing in use as a tool in genealogical research. Test results can be used to confirm a suspected connection between two families or disprove a connection.

Chromosomes are paired threadlike "packages" of long segments of DNA contained within the nucleus of each cell. In humans there are 23 pairs of chromosomes. In 22 pairs, both members are essentially identical, one deriving from the individual's mother, the other from the father. The 23rd pair is different. In females this pair has two like chromosomes called "X". In males it comprises one "X" and one "Y," two very dissimilar chromosomes. It is these chromosome differences which determine sex.

The presence of a Y-Chromosome causes maleness. This little chromosome, about 2% of a father's genetic contribution to his sons, programs the early embryo to develop as a male. It is transmitted from fathers only to their sons.
Most of the Y-Chromosome is inherited as an integral unit passed without alteration from father to sons, and to their sons, and so on, unaffected by exchange or any other influence of the X-Chromosome that came from the mother. It is the only nuclear chromosome that escapes the continual reshuffling of parental genes during the process of sex cell production. It is these unique features that make the Y-Chromosome useful to genealogists.

The Y-Chromosome has definable segments of DNA with known genetic characteristics. These segments are known as Markers. The father passes an exact copy of his Y-Chromosome to his son. This means that the markers of the son are identical to those of his father. They remain unchanged through the generations for hundreds of years.

Female DNA is not as as positive a marker as the Y-Chromosomal for men because the X-Chromosome passed from mother to daughter is not always identical.

Are you still with me? What does this tell you about the differences in men and women?

1. Men never change

2. Women are hard to figure out