Despite being clear that Princey, Logic and Dad are different characters from the Prince Guy, the Teacher Guy and the Dad Guy from Sanders Shorts
(2013), the dates when each of the "Sanders Guys" characters were introduced in the Shorts series have been widely accepted, both by the creative team and the audience, as the birthdays for the Sanders Sides characters, and each birthday is celebrated with great fanfare, both by Thomas Sanders
and his followers, who send Thomas lots of fan-art for the celebration that Sanders willingly shares on his Twitter, Instagram and Tumblr accounts.
Morality's birthday has been established on January 15, as the Dad Guy was first introduced on January 15, 2014 in Sanders Shorts: Dad's Jokes Just Became Legit
(2014); Princey's birthday has been established on June 4, because the Prince Guy was first introduced in June 4, 2014 in Sanders Shorts: Fairytale with a Twist: Sleeping Beauty
(2014); and Logic's birthday has been established on November 3, as the Teacher Guy was first introduced on November 3, 2014 in Sanders Shorts: These Troublemakers
The rest of the birthdays coincide with their first introduction on the Sanders Sides series as they debuted on Sanders Sides. Anxiety, on December 19, as he was first introduced on December 19, 2016 in Sanders Sides: Taking on Anxiety with Lilly Singh
(2016); and Deceit on February 3, as he was introduced on February 3, 2018 in Sanders Sides: Can Lying Be Good?
(2018). The Duke, even though there hasn't been time to celebrate a birthday for him yet since it's been less than a year since his introduction, it is presumed to be celebrated on June 25, as he was introduced on June 25, 2019, in Sanders Sides: Dealing with Intrusive Thoughts
Joan however, clarified in their Tumblr account that none of these dates is canonical in the plot of the series. They clarified that what is being celebrated is the first introduction of the characters, not the characters' canon birthdays, because, in the story, all of the Sides share the same birthday as character Thomas because they are parts of Thomas. They wanted to make it clear that all of the Sides have the same gender, sexuality and birthday as Thomas to avoid them being called "personalities" plural and hint that Thomas would be a character with dissociative identity disorder, which is not what the team wanted to portray in the story. See more
Until next time, take it easy, guys, gals and non-binary pals! Peace out!