The family trees are of classes of cats from Kitten Academy (KA), a website that supports a 24/7 YouTube stream of foster kittens, as well as some produced, archived videos.

The first part of the puzzle is identifying the numbered cats, as determined via the site’s Alumni and Mewspaper sections.

Per standard family tree notation, circles are female, squares male. Adoption is often shown as dotted lines (here indicates unrelated kitten adopted by a MomCat) or brackets (adopted by KA, i.e. “Faculty”). Non-purple outline indicates collar color (if any) while at KA. Shapes are colored to match their general fur pattern. Tabbies are shown as swirls whether swirled or striped. Torties similarly shown with a standard fur pattern, even though they too vary a lot. Long-haired cats are shown with an extra ring of “floof” outside their shape outlines.

Black slashes are used traditionally, to indicate “Sads.” Each obliged KA to reiterate their “No Sads” policy. This may help confirm the timeline. Classes are generally ordered by their “graduation” (spay/neuter) date. The background color changes with the year. 2015 through 2017 are based on Alumni pages. 2018 contains all the classes that do not (yet) have Alumni pages, but are mentioned in the Mewspaper, in order of arrival at KA. (Several cats came in and graduated before all of the “Cat Trees” had been adopted.)

The last letters of the numbered cat names, indicated by their tails in the flavortext, spell out the phrase:

DATED ONES AT END IN THIS TOWNS WISHES FILM ON YT CHANNEL

On Kitten Academy’s YouTube page, there is a recent video titled “Christmas and New Year’s Wishes 2018.”

The cats at the end credits of the video are linked by date to their Mewspaper graduation announcement, with the exception of Chai (whose date links to a Mewspaper entry solely about her) and Elsie the dog (whose adoption predates KA; her date matches a Mewspaper that featured her).

The last letters of their names spell out the answer EXOTIC SHORTHAIR.