Sounds a bit fo a myth to me - more to do with personality and circumstances than sex I feel. ds was fine but dd has had it really badly. It started from before 5 months and she can still panic and put up a fight being left at 3 1/2.
I think all children go through this. It's a normal part of development. Their way of telling you that you're important and they'd rather be with you. However, if you've got good childcare the "anxiety" lasts not much longer than it takes you to leave the building they are in and then they're fine. DS protested for 10 months for the two days when I left him at nursery. The nursery told me that within 30 seconds of me leaving he was fine. It started at about 13 months with him (before that he went in happily) and stopped when he was nearly 2. Now just clings a bit but goes happily to one of the carers/nursery nurses.
separation anxiety is a perfectly normal part of development, when a child starts to realise s/he is a different person to mum (or whoever has been the main carer) and gets freaked when you leave the room etc. i admit i settled my girls at nursery when they were 7 mths so this stage would be "easier" to cope with and i believe it was. also different children develop different degrees of this/ways of coping with realising that the world is a big place and think your friend is putting the fear of god into you unnecessarily