"But there are no biological causes we can determine."

It is very difficult to separate biological cause from learning effects due to epigenetics.

What he means is that most sexual pain has a biological cause, but it usually also causes psychological issues.

"No evidence was found to support a biological cause."

No biological or physical cause could be found and the studies were abandoned.

No plausible biological cause for the association is yet evident.

Rather than biological or psychological causes, this branch of the School identifies "society" as the cause.

The actual biological cause of migraines is still under investigation.

Some other biological cause(s) still place these children more than 2 standard deviations below average height.

"Trying to find a biological cause for our rites of purification."