A Guy Who Loves Detective Stories…or Not

Riddle: Megan was looking for a guy to go out with. She found a guy named Henry, and she found out that the guy loved detective stories. Megan texted Henry later that day, asking about his affinity for those kinds of stories, and he said, "Detective stories are SO cool! My grandmother even knew Sherlock Holmes!". Megan responded, "I'm not going to date a liar like you!". Why did she think Henry was lying?

Answer: Henry's grandmother couldn't have known Sherlock Holmes in real life because Sherlock Holmes is a fictional character.

Source: https://www.riddles.com/index.php/11427

Megan was looking for a guy to go out with. She found a guy named Henry, and she found out that the guy loved detective stories. Megan texted Henry later that day, asking about his affinity for those kinds of stories, and he said, "Detective stories are SO cool! My grandmother even knew Sherlock Holmes!". Megan responded, "I'm not going to date a liar like you!". Why did she think Henry was lying? — A Guy Who Loves Detective Stories…or Not by Gabriella Simonetti Riddle