The relationship between a parent and a child is instinctual and stems from basic human nature.
父母与孩子之间的关系是本能的，源于人类的本性。
《柯林斯英汉双解大词典》
2
During critical situations, especially when a threat is perceived, the outer core loses control and fails to regulate the impulses and instinctual responses coming from the primitive brain.
在危急情况下，特别是在察觉到威胁时，外核会失去控制，无法调节来自原始内核的冲动和本能反应。
3
We even share some basic instinctual quantitative reasoning with distant non-mammalian relatives like birds.