How does $? behaves with functions executing in background?

Imagine I have the following function:

```
#!/usr/bin/env bash
doInBackground() {
    #We call a function
    someOtherFunction someParam
    if [ $? -eq 1 ]; then
        echo "was one"
    else
        echo "was not one"
    fi
}

```

And that I call it multiple times this way:

```
doInBackground &
doInBackground &
doInBackground &
doInBackground &
wait

```

If they are executing simultaneously, what will $? return? Will it be affected by the other executions? What is the behavior in this case?