I did in vivo brain surgery using animal models. The rats were all from specific strains geared towards being almost genetically identical as possible. I can sa

I did in vivo brain surgery using animal models. The rats were all from specific strains geared towards being almost genetically identical as possible. I can say, each one of these rats developed in a completely unique way from behaviour through to anatomy despite being kept in a highly controlled environment (same food, light, water, routine, conditions etc). Even the location of their brain anatomy differed highly. So even in almost genetically identical models, there is a high degree of individual variability.