Parental influence on level of extroversion in offspring

Seeing major differences in my first and seconds level of extroversion. My first was definitely easily described as a velcro baby and has become a very extroverted toddler. My second is fine on her own and seems to be developing into an introvert. It’s my understanding that introversion and extroversion are set traits. My question is when in childhood does this personality trait become set or fixed? And can anything that a parent does previous to this age be influential? via /r/ScienceBasedParenting https://ift.tt/mrXbh18