we were hoping for a three year age gap with our DS so started TTC just after he turned two but we are still trying (we are on our our first ivf cycle). This means that there will be about a 4 and a half year age gap. my brother and i are 4 1/2 yrs apart and we get on really well. i guess really it is each to thier own. everyone has different reasons for choosing age gaps and others have just got to wait for nature to comply!