Online handles and genetics

In Homestuck there is a connection between genetics and twenty-two online handles. GCAT is a common presentation of the pairings of bases in the double helix structure of DNA, in Homestuck, sixteen abbreviations of online handles can be derived from two-letter combinations of GCAT. Four of them are used by the eight kids (each one used twice), and the other twelve are used by the trolls. Calliope's handle, uranianUmbra, expands upon the genetic pattern from DNA to include RNA, instead using the letter U, corresponding to uracil, which replaces thymine (T) when information is copied from DNA to RNA. undyingUmbrage also shares the same abbreviation however it appears in lowercase. A connection can also be made between these two handles and genotypes, where dominant genes are represented by uppercase letters and recessive genes are represented by lowercase letters, so that UU would represent being homozygous dominant for a genetic trait, and uu would represent being homozygous recessive for a genetic trait.

At the start of Homestuck, John uses the handle ectoBiologist, thus breaking the pattern, however in flashbacks prior to the change he is shown to use a handle that does fit the pattern but later changed it to avoid the trolls.

All the post-scratch kids have chumhandle abbreviations that match that of the ectobiological sibling of their corresponding pre-scratch kid: Jane/Jade, Jake/John, Roxy/Dave, Dirk/Rose.

The God Cat is also known as "GCat".

Each of these two-letter pair is the abbreviation used for an online handle of one of the trolls or kids (except for John):

Trivia

 * The kids' combinations do not include the letters A or C. Conversely, all of the trolls' combinations include either A or C.
 * Of the four pre-Scratch kids, John and Dave have or had GT and TG, while Rose and Jade have TT and GG, resembling the male XY chromosomes and female XX chromosomes. The two remaining same-letter combinations (AA and CC) do belong to female trolls, but the remaining female trolls are GA, GC, AC, and AG; the number of female trolls would be limited to two if the pattern was not broken. Of the post-Scratch kids, Jane and Jake continue the pattern having GG and GT, however Dirk and Roxy break it having TT and TG, respectively.