"After my Mum died we found letters, tied in a bow from my Dad from when he worked away in London in the 60s," she tweeted.
"My crying sisters and I held hands, opened one and the whole thing was about how much he missed shagging her, apparently a bit of a goer. Didn't read the rest."
With the tweet going viral with over 90,000 likes, one commenter tried to see the bright side to the situation saying at least her parents loved each other.
"Must have been a comfort to know there was serious passion there though?" one wrote.
Morven replied, "Um, kinda. We already knew they were in love and all that but seeing sexual acts that your Mum has performed on your Dad written down is another kettle of fish".
Another user wrote, "Sorry for ya loss but that's hilarious" with Morven saying in reply, "Thank you, we laughed too. After we stopped gagging".
Others responded to the tweet with their own horror stories.
@Olwenmcg wrote: Similar thing after my grandparents died - my granny kept a diary and gave my grandpa marks out of 10 for his "performance".
Another said: "My BF was painting his grandparent's house for them they had an old bookshelf that hasn't been moved in years. When he moved it a few pictures fell off the top. It was pictures of his grandma's breasts with 'you do miss them' written on them, lol."