In this blog post from June 19th, 2018, veterinarian Dr. Karen Becker discusses the importance of socializing and habituating a kitten between 8 and 15 weeks of age, a critical developmental period. If you are adopting a kitten from an individual, shelter, or rescue, you want to make sure they have been doing this, and you should ask for detailed specifics on what they have done. If they are not socializing the kittens, you may want to look elsewhere. –
FMI – https://healthypets.mercola.com/sites/healthypets/archive/2018/06/19/kitten-socialization.aspx