None of my toddlers have been that affected by it to be honest. When i had my second my first was only 20 months old and i'd only stopped breastfeeding her 6 months before, she was interrested and facinated but just seemed to know what and why i was doing it. When i had my third my second was 21months and my first was 3 1/2 , My eldest wasn't bothered in the slightest after being exposed to it with her younger brother, but blimey 21 month son was transfixed the first few times he saw and wanted a turn which i casually allowed, he tried it once then wasn't bothered lol, Now expecting number 4 and still breastfeeding number 3 who will only be 15 months old when this little one arrives in november. I'm sure they will all be great. A good book i and other friends have found is "We like to Nurse"
http://www.amazon.co.uk/We-Like-Nurse-Chia-Martin/dp/0934252459/ref=pd_cp_b_2.
Good Luck
Jo xxx