At present probably Traits are more of a statistical guess.
The BRCA1 and 2 DNA tests that look for the altered gene in breast and ovarian cancer does not provide a conclusive yes/no answer, only 5-10% of those affected or likely to be affected carry the altered gene.
In my mind Traits are a marketing ploy, the My Heritage Traits are way off the mark with me and my Wife. No reason why Ancestry should be regarded as anything more than a bit of fun.