Its well knows that siddhis exist. My query is does the offspring inherit the siddhis of the parent. Even if the parent obtains the siddhi after the offspring is born. ?
That’s a pleasant thought: inheriting siddhis. I wish it were true even at the level of more-worldly qualities, such as artistic talent or business acumen. Alas, our inheritances are determined more by our personal karma than by anything else.
Of course, if your karma placed you in the family of a person with some kind of power (whether spiritual or worldly), the force of magnetism might help you acquire at least some of that power if you are actively receptive to it. So if you have a parent with siddhis, you can try that.
However, remember that most of the siddhis one hears about are, in general, spiritual dead ends – and worse than that, they are traps to be avoided. Far better to focus on devotion and attunement with God if you want to progress spiritually.