Stranger anxiety is a normal phase in the developmental process of an infant, which reaches its apex, more or less, between 6-12 months in age (though it may certainly linger longer). While as parents,we often get embarrassed when we bring the in-laws, best friends, coworkers, and neighbors around and our children are screaming their heads off out of fear -- the "stranger-anxiety" phase is very typical, and assumingly an evolutionary trait that we as humans have kept because of the proverbial "stranger-danger" sentiment.
However, I was wondering if children who have been diagnosed with Willam's Syndrome (WS) skip the "stranger-anxiety" phase all together? Yes, William's Syndrome has a long list of physical and mental abnormalities, but they are also known for being excessively (abnormally so) friendly and social... so are they developmentally delayed in the sense that they skip the "stranger-anxiety" milestone? OR do they not start becoming more extroverted until they are older? (Read more about Willian's Syndrome here: https://en.wikipedia.org/wiki/Williams_syndrome).
Since apparently that have a great memory of faces, then they indeed recognize that they are in the presence of a stranger, but this does not stir fear in them in any way, right? My friend's daughter has WS (never had the chance to see if her daughter skipped the "stranger-anxiety" phase as a baby), but I know that my friend is always keep a constant eye on her daughter in fear that her daughter may be abundantly social and trusting and make herself vulnerable to kidnapping and other horrendous incidents.
Why are people with WS so extroverted? Why do they display a strong sense of empathy?