At what age are you too old to sleep in your parents bed no matter what?

It think you dad is over-reacting. There is way too much over thinking and perversion when topics like this come up. It's a bed, it's not different than anything else. Families lay on picnic and beach blankets together, cram onto the couch together, sleep in the same tent when camping, the list goes on. A teenager sleeping with a parent because their emotionally unable to sleep independently is a problem, going in there because you need to be close to your parent during an illness isn't.