My parents are both sp dom. (Almost) all of us have different Ennea cores though so interestingly, we manifested the instinct in different ways.
That being said, sp was definitely not neglected in my family. My mom was very sp of the most stereotypical kind, if I compared myself to her and if she was the definition of sp I might have considered myself sp-second. Personally, I don't think nurture had much to do with it, because while we're all sp doms we all manifested it differently and even argued on what to be sp about and how. I also always had my own preferences I stuck to no matter what kind of specific sp preferences or methods my mother tried to pass on to me.
To elaborate, she was likely either E6 (CP) or 8 core, and she was typical- expansive, voracious, go-getter and very high activity in expanding her security, would shove people aside if it meant more resources for her. Extremely, ridiculously anal about environment, health, finances, sometimes to a seemingly paranoid degree.
My dad & I, both E5 cores, were similar yet in some aspects entirely different- we both favoured withdrawing, denying needs, and minimizing- but he went all the way. Eg; he went vegetarian and barely bought new clothes, and glorified a 'spiritual life' of simplicity and non-attachment, something unthinkable for my mom (not as unthinkable for me, but I definitely cannot glorify such an impractical lifestyle and would not do it if I had resources).
My brother #1, E9 core, was also extremely minimizing and even self-neglecting but clung tight to things he did have that would give him security- very non-confrontational for the sake of maintaining his perceived peace / autonomy- his is not as obvious as the rest but if you paid attention, you'd realize that his attention goes a lot to maintaining and protecting say, his personal space, his belongings, his autonomy- just, by withdrawing instead of by confronting. For example, my mother would press and get aggressive to establish dominance, while my brother would build rapport so that his space would not be intruded upon.
Personally, even as sp-dom myself, I disagree with the methods of all them three (my father, despite similar cores, was still also too extreme for me).
Mother - sp/so
Father - sp/sx
Me - sp/so
Brother #1 - sp/sx
Brother #2 - so/?