If I ever were to have a DNA test done for myself for the purpose of genealogy, would it be most accurate to have myself (female) and my father tested, or to just have my full-brother tested to get the results?
or should this question go under biology...

Let's say both cousins are related through their grandmother on their fathers' side, but neither have parents or grandparents still alive... so that rules out the possibility of getting a dna sample from them. But if 2 cousins were to take a dna test themselves, is it possible that they could determine whether or not they had the same grandfather on their fathers' side?

is there any way you can get a paternity test for free

I live in New York and there's a girl pregnant for me in Guyana South America. Is there a way where I can get a DNA test without having to go there? How?

A few years ago I had my 2 older kids tested against a man I believed 2 be the father. We felt like the test was wrong and that my husband was actually the father of my 6 year old. So we had my 6 year old re-tested against my husband and found out that my husband is actually the father of my 6 year old and that they had accidentally tested my oldest son twice against the other man. Does that mean that the other mans dna test is now invalid? What rights does my husbnd have now that he knows he is the father?

This test goes like this. If you suspect your partner or spouse , you can send sample of suspected material ( Like Hair, fibers of cloth or strains of blood or semen on bed sheet ). It is then compared with your DNA sample and laboratory confirms whether the DNA sampling is matching with you or not.

These tests are becoming very popular in western countries.

Don't you think these kind of tests would lead to social sickness ?