My mom is 30% Spanish my dad doesn't have any Spanish. I'm 29% Spanish. ( (We all took the DNA test) how can I be just as Spanish as my mom if my dad wasn't at all? shouldn't I only be 15%?
Your logic is totally correct, and you should be 15% in that scenario.
However, that is assuming the percentages are totally accurate, which they are not. The percentages are likely plus or minus 20%. So your 29% could mean you're anywhere from about 10% to 50%.
It is unfortunate that the DNA testing companies are implying precision in saying that you are 29% instead of giving the range to indicate the level of uncertainty.
Similarly bad, they show you small percentages such as 3% Irish or 1% Eskimo that are more likely than not to really be zero.
Ancestry doesn't give you a Haplogroup. My daughter in law shows 100% east Asian, thats maybe 3 billion people. 23andme breaks it way down to small amounts of Chinese and Korean, which her matches support what we are seeing. A lot of the Ancestry matches do not appear on GEDmatch as good matches. She has only 11 5th cousin matches on FTDNA, I don't think they have a very large database, well thats not their fault, but if you spend money and end up with nothing its disappointing. My feeling is if you are white and looking for you mother or father Ancestry is OK. If your are not white and looking at trying to figure out who you are or clues about your family then 23andme seems to make more sense. Maybe FTDNA will better in twenty years.