The short answer is that both siblings should take a DNA test, if possible. There are multiple types of DNA tests and the one that is right for you and your siblings will depend on what you would like to achieve with the results of the test.
Do male and female siblings have the same DNA?
Because of recombination, siblings only share about 50 percent of the same DNA, on average, Dennis says. So while biological siblings have the same family tree, their genetic code might be different in at least one of the areas looked at in a given test.
How accurate is a sibling DNA test?
How accurate is DNA testing for siblings? Sibling DNA testing is 100% accurate and can produce very conclusive results. Generally, the analysis can be performed with only two or more brothers or sisters, however we recommend adding any available known parent(s) to help increase conclusiveness.
Can two siblings take a DNA test?
A DNA sibling test will test the relationship between two or more individuals to assess if they are biologically related as siblings. Sibling tests can also be used to provide reliable parentage testing when one parent is deceased or unavailable.
Do male siblings have the same DNA?
So in almost all cases, a biological female will have two X chromosomes and a biological male will have one X and one Y chromosome. These variations in X and Y chromosomes mean that brothers and sisters can never have identical genotypes. However, brothers will have the same DNA on their Y chromosomes.
How do I know if my sibling has the same father?
Yes; sibling DNA testing can establish whether brothers and sisters share either a biological mother or father (half siblings). Can a DNA test determine if siblings have the same father? Yes; testing the DNA of siblings can determine a shared biological father without his involvement.