A gay explanation?

Genetic tug of war linked to evolution of same-sex sexual behavior in beetles | EurekAlert! Science News

In this study the scientists looked for evidence to support the
theory that genetic links exist between SSB and other characteristics
which carry benefits in one sex but not the other. Thus, SSB in one sex
could occur because genetically linked traits are favored by natural
selection in the opposite sex - the genetic tug of war.

The scientists based their hypothesis on the fact that most genes
are expressed in both males and females and often code for more than one
characteristic. For example, previous studies have reported that the
same genes that code for SSB are also the genes that code for mobility.
Mobility is known to be costly to female seed beetles as they do not
need to range as far as males to mate.

To test their hypothesis, the team of scientists selectively bred
male and female beetles to display increased SSB, studying how this
affected their mobility and reproductive success compared to beetles
that had been bred to display decreased SSB. The scientists showed that
when a particular sex had been bred for increased SSB, siblings of the
opposite sex enjoyed an increase in reproductive performance. They also
showed changes in traits such as mobility and sex recognition after
selective breeding on SSB, providing evidence for genetic links between
SSB and these traits across the sexes, according to the researchers.