A five-year study run by Indiana University’s Kinsey Institute for Research in Sex, Gender, and Reproduction proves what many in the scientific community have always suspected: having children significantly lowers the IQ of both male and female parents.

Researchers at the Kinsey Institute began their study in 1999 by giving 200 married couples who were planning on starting families within the next four years Intelligence Quotient (IQ) tests. By 2003, all but 27 of these couples had conceived.

Another IQ test was given to each set of parents successful in conceiving and birthing a baby six months after their child was born. These results were compared to the previous intelligence tests.

In every single one of the 173 cases, both parents scored at least twelve points lower on the second IQ test, with the majority of parents losing twenty or more IQ points.