You can report on students family structure if you have recorded this information on the student's profile
You can then report on this using the Custom Report via Reporting > Custom Report
Click 'New Report' to start.
On the right hand side, there is the 'Display Columns' section.
From here, select the 'Features' tab and tick "Family structure"
Then, click "Run Report" at the bottom of the screen
Once the report has run, you can filter the 'Family' column for what you want by typing in the white filter box and pressing enter. E.g. 'Single' to show the single parent families -