If you’re endeavouring to find your ancestors and create your family tree, have you considered taking a genetic DNA test?
Well before you do, firstly consider what you want to achieve from an Ancestry DNA Test.
Many reviews of Ancestry DNA tests provide an overview of what the process is like, what you can expect from the service and delve into privacy issues. A conversation piece over drinks perhaps, but does % ethnicity and the like actually help you find that elusive grand parent? The answer is both yes and no.
My preference is to use AncestryDNA: Genetic Testing
Why? The more people in the database, the more likely you are to find a match and perhaps a clue to pursue in finding that missing piece of the puzzle. It also helps if those who have taken an Ancestry DNA test allow on-line access to the family tree they have made. Allowing publication of their family tree eliminates emailing them and thus is quicker in making comparisons – eliminating the known and following up the unknown. It is possible someone has published or knows of grandparents along the tree you didn’t know before.
If you are looking to prove you are related to Prince William, Duke of Cambridge or other dynasties, then Ancestry DNA isn’t likely to directly prove it genetically! However, by expanding your family tree you might find links back into British and European royal families.
Having access to others family trees from close or distant relatives makes it easier to make shortcuts building your own. I have found it useful in finding potential bedhopping fathers 3-4 generation back when birth records don’t record the father. So if your goal is to find more ancestors or a Father/Grand Father then yes it can be useful. But beware it can also exclude someone you think is a father/grand father.
The other 
reason to undertake an Ancestry DNA is to help confirm you are on the right track building your family tree at least 4-5 generations back. Confirmation by matching to other family trees etc can help provide confidence your methodology and tree is true and correct – genetically!
Now back to % ethnicity – If you already have a number of generations in your family tree the
n % ethnicity probably isn’t going to be any surprise. If not this information might point you in a particular geographical direction of researching. Perhaps you can debunk longstanding family myths you’re from viking stock or prove them. But if it does throw you a curve ball, this could be something useful too.
Lastly, if you’re a social person and your goal is just to connect with relatives across the globe, then yes Ancestry DNA can assist.