I've rarely left DD and usually someone has come into our home so she has been in a familiar environment.

It is/has not done her any harm at all. Infact, DD is very outgoing and is not scared of strangers at all so I don't fall for the line that they have to be left with people to get used to new people for socialisation.

DD is mega-friendly and has been handed around on trains, toddles up to people in cafes, waves to people walking past us in the street, insists on playing peek-a-boo with every checkout chick, ran back down the footpath yesterday to give the next-door neighbour a kiss, runs into other neighbours' gardens who she's never met and starts dancing for them etc. etc.