Puppy Socialisation why it's so important
Puppies have a narrow window in which to experience as much of life as possible, for most dogs this is between 12 and 20 weeks old (depending on breed). Failure to socialise your puppy can result in fearful or aggressive behaviour towards something that is unknown.
Obviously the biggest drawback to early socialisation of your puppy is vaccinations, as your puppy must not be exposed to any source of infection until their vaccinations are complete.
However this doesn't mean we need to lock our puppies away, they can be socialised with people i.e. men, women, children (closely supervised!), teenagers, old people, disabled people and people using walking sticks and wearing hats.
Once their vaccinations are complete we can then socialise them carefully with dogs - as many different breeds as possible (but only where the other dog likes puppies, as all early experiences need to be positive).