Please solve the programming task below using a self-contained code snippet in a markdown code block.

There is a family tree rooted at 0 consisting of n nodes numbered 0 to n - 1. You are given a 0-indexed integer array parents, where parents[i] is the parent for node i. Since node 0 is the root, parents[0] == -1.
There are 105 genetic values, each represented by an integer in the inclusive range [1, 105]. You are given a 0-indexed integer array nums, where nums[i] is a distinct genetic value for node i.
Return an array ans of length n where ans[i] is the smallest genetic value that is missing from the subtree rooted at node i.
The subtree rooted at a node x contains node x and all of its descendant nodes.
 
Please complete the following python code precisely:
```python
class Solution:
    def smallestMissingValueSubtree(self, parents: List[int], nums: List[int]) -> List[int]:
```