There are two main pathways to excess hair growth in females, one that is dependent on hormones and the other that is hormone-independent. Specifically, if a female has higher than normal levels of androgens (male sex hormones) or are genetically sensitive to androgens, then she is more likely to grow lots of hair. The other type is idiopathic, for people who have average androgen levels but still seem to have excess hair.
In the same study among Japanese women that investigated the genetic influence on double-fold eyelids, excessive sweating, age spots, eyebrow thickness, and hair texture, investigators found three new loci associated with excessive hairiness. These loci were associated with the regulation of various genes such as BCL2, which has already been found to regulate hair follicle growth. Differences in BCL2 gene expression may be changing the timing at which follicles die (i.e. when the hair follicle stops growing), which may ultimately affect how hairy you are. Check out the full details of the study here: https://www.ncbi.nlm.nih.gov/pubmed/29895819
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