I have a table records(ID, ParentID) containg this data

ID   ParentID  
1    null  
2    1  
3    2   
3    4  
4    5  
6    null  
7    6  

If you draw this table in hierarchy as a family 1,2,3,4,5 will be related to each other.

I want to find a way, where I can pass an ID like 3 it give me the others family members using SQL or using C#

3 - result 1,2,4,5
2 - result 1,3,4,5
6 - result 7
and so on

I want to find my parent and his parents and childs and my child and his childs
LIKE THE EXAMPLES