Researchers could use the Swedish bio bank to get fairly accurate numbers as the database was established in 1975 and include all that was born between then and

Researchers could use the Swedish bio bank to get fairly accurate numbers as the database was established in 1975 and include all that was born between then and now. As for the numbers in the study there is several factors that either increases or decreases the rate. Those that decrease the rate are studies that requiring informed consent, marriage, and high social economic status. For groups where all three is true you get rates around or below 1%, and for paternity testing labs which has the opposite of demographic you get around 20%. The true average is thus hard to establish as almost all existing studies has biased sampling from all of those factors.