The Difference Between Girls and Boys at 6 years of age

Is it biology? Is there a female and a male brain or are our differences down to our life experiences from an early age?
The truth is, despite trying to treat them the same I have found for many reasons my twins have had different lives from an early age.
1. The way other people treat them.  Other people give them toys to play with based on gender even if I do not.
2. Their personalities make them so different that they way the rest of the family interact with them is unique for each twin.
3. Medical issues have impacted on one child's life.

Now that they are 6 my daughter is maturing that little bit more than my son and I guess I can expect to see quite a gap in maturity and behaviour as they approach the pre-teen years.  Perhaps the difference in age for entering puberty (younger in girls and older in boys) also affects our brain but hard to know whether that affect is due to biology or life experience?
http://mrstaraplumbing.com/2014/09/30/is-there-such-a-thing-as-a-male-or-female-brain/

Only one twin with allergies - are the first year & stomach bacteria important?

As one of my twins has multiple allergies - peanuts, pecans, walnuts and contact with nickel, I was fascinated to watch the recent Horizon TV programme, evidence was presented that gut flora is important and this is colonized during the first year of life.

What was interesting to me is that as far as I can recall my fraternal twins had the same first year: both breast fed, both natural birth, stayed together in the Special care baby unit for the first two weeks and mum did have antibiotics at least once (may be more) in that first year, whilst breast feeding.

These things may all impact on gut flora but in fact, as stated, only one of my children has allergies so there must be more to it.  I think there may be something in his genes, as studies among identical twins have also found strong evidence of a genetic link.   The bacteria hypothesis is a way of explaining the incredible rise in allergies, however, so that now about 30% of the population may have some allergies.