Idea easily spread about me having twin (4)
I believe the answer is:
meme
'idea easily spread' is the definition.
I can't tell whether this definition defines the answer.
'about me having twin' is the wordplay.
'about' is an insertion indicator.
'having twin' becomes 'em' (I can't justify this - if you can you should give a lot more credence to this answer).
'me' placed around 'em' is 'MEME'.
Can you help me to learn more?
(Other definitions for meme that I've seen before include "Behavioural trait" , "online phenomenon" , "Often trite image" , "Cultural feature passed on by imitation" , "Question that spreads on the internet" .)