This DNA test was entirely unknown to Tiffany Mamet.
Originally, when Tiffany Mamet returned to Imperial Capital seeking protection, claiming vehemently that the child was Gem Atkinson's and insisting that the child must stay, Nathan Mamet agreed to keep the child temporarily to stabilize Tiffany's emotions. However, being someone who never allowed for errors in his affairs, he wanted Isla Mamet to prove that the child was indeed Gem Atkinson's.
The life-saving umbilical cord blood did not necessarily have to come from direct relatives, as non-direct relatives could also be possible donors.
In order to prove it to Nathan Mamet, Isla secretly conducted a DNA test through amniocentesis during a routine examination of Tiffany.
Of course, it was extremely difficult to obtain samples of Gem's hair or blood. However, at that time, Eleanor Spencer Atkinson was close to Julius Mamet, thus it was very easy to get a sample of Eleanor's hair.
