I think what you are ultimately looking for is found here: Help:Adoptions and Multiple Parents.
"WikiTree only allows a person to have one mother and one father. This provides the basic structure for family trees."
There are ways to include information on biological or adoptive parents, it just depends on how you choose to provide that information.
For instance, you could connect your profile to your biological parents (helpful for DNA) and then use the Adopted Child template to indicate your adopted family and link to their tree.
Alternatively, you could connect to your adopted family and then make reference to your biological parents using the same template noted above.