Susan and Mary Test (also known as The Test Twins) are Johnny's genius twin sisters and daughters of Hugh and Lila, who frequently use him as a lab rat for various inventions.Her sister is more open-minded, and Mary is frequently proven correct. Susan seems to be less open-minded than her twin Mary and tends to be less conservative, as she speaks her mind much more often.Their brother(Johnny) is a mischievous and unpredictable boy who causes many problems is very VERY reckless and not wort trust