>> Observational studies of this type cannot show causality >They can: sibling comparisons. But then they get much lower concordance so they come up with vari

>> Observational studies of this type cannot show causality >They can: sibling comparisons. But then they get much lower concordance so they come up with various ad-hoc hypotheses to explain it, instead of acknowledging the negative result. This is an hypothesis generating paper, using a highly suspect methods. Not a discovery.