What Are Haplogroups?
A haplogroup is a global extension of your family. Depending on the sequence of genetic markers that they carry in their cells people can be grouped into specific ancestry DNA haplogroups. A group of individuals belonging to the same haplogroup can trace their roots back to a common ancestor. This usually also points to a specific geographical point since each haplogroup has a definite migratory pattern. If you want to know more about the science behind these ancestry DNA haplogroups, you can refer here
Ancestry DNA Haplogroups
Besides their common geography and migratory pattern haplogroups are characterized by a de novo mutation. These mutations are carried and undergo vertical transmission through subsequent generations. When sufficient number of people carry this single base change in their DNA sequence they will together form a haplogroup. Needless to say that it takes thousands for sufficient individuals to carry the mutation (now called polymorphism) and form a haplogroup.
Are Haplogroups permanent?
Haplogroups are not permanent. They have in the past phased-out and formed new ones. Though some of them have successfully sustained themselves to the present day. Nearly 50% of all Europeans have the haplogroup H. This means that they have all descended from a single person who had lived thousands of years back.
What does nearest maternal or paternal ancestor indicate?
The head of the maternal or paternal haplogroup within whom the set of gene variation first occurred.
How do New haplogroups begin to form?/Are there any newly formed haplogroups?
New haplogroups are formed when a gene mutation occurs in someone from a particular ancestral clan. However, it is not before many generations that enough people carry the mutation for it to spread, become prevalent to be considered as a haplogroup. Any haplogroups that start forming today will not be recognized as new ones for centuries, or even millennia. The haplogroups that form today will eventually be able to be traced back to the earliest known person to carry the mutation, just as today’s known haplogroups can be traced back to the earliest known person to carry it in the distant past.
Everyone inherits the DNA within a cell organelle called the mitochondria from the mother only. Hence maternal haplogroups are defined using variants in an individual’s mitochondrial DNA. Another interesting fact about the mitochondrial DNA is that it does not undergo the process of recombination with other types of DNA (like your nuclear DNA). This means it is inherited as it is with limited changes directly from you mother. Therefore individuals with the same maternal line will share the same maternal haplogroup. Each maternal haplogroup traces back to a single mutation at a specific location and time.
Y Chromosome Haplogroups
Y chromosome is found exclusively in males (with the exception of individuals with Klinefelter’s syndrome). The Y chromosome undergoes genetic recombination with the X chromosome at a specific region called the pseudoautosomal region. In other words, this region of the Y chromosome behaves like an autosome in spite of being a sex chromosome. However this a very small fraction. Around 95% of the Y chromosome remains unchanged across generations. This is used to trace your paternal ancestry. Though females do not have a Y chromosome, they would share the same paternal haplogroup with another male member of the direct line (e.g father, brother).