Ronald D Moore's original idea was for Jeremy Aster to recreate his mother on the holodeck, however Gene Roddenberry nixed the idea, believing in the 24th century children would have a greater acceptance of death.
Patches is a calico (tri-color) cat. The character refers to him as "he," very rare. Color is decided by the X chromosome, for a male cat to be calico he must have double X and the Y chromosomes, instead of the common X & Y. Of course being the future it could be genetic engineering, but to what purpose?