No one messes with Bristol Palin’s brother, Trig! The mother of two defended her sibling after posting a photo of him for World Down Syndrome Day on her Instagram account.

“World Down Syndrome Day!! I don’t know how our family got so lucky to have this handsome boy. Light of our lives without a doubt #theluckyfew #TrigPaxson #T21 #mybrotherhasmorechromosomesthanyou,” she captioned a photo of the little boy, 7, wearing a pro-Donald Trump hat.

RELATED: Bristol Palin’s Brother Trig Cradles Baby Sailor

Bristol’s mother, former Vice Presidential candidate Sarah Palin, previously publicly endorsed the GOP hopeful. But one commenter chose to mock the little boy for his attire.

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Soon after, Bristol fired back, commenting, “@hrhbeth I wish I knew who you were, hope you don’t happen to be a nurse with any child with Down syndrome. You are pathetic.”

MORE: Bristol Palin Responds to Conspiracy Theories About Her Daughter’s Birth Date

In January, Bristol showed even more pride for her little brother, sharing a photo of him cradling her infant daughter, Sailor, and living the baby a sweet kiss.

“Trig officially loves her #mybrotherhasmorechromosomesthanyou,” she captioned the shot.

Bristol is also mom to son Trip, 7. She posted another pic of Trip and Trig on Monday, writing, “One more picture for World Down Syndrome Day!! Love seeing my newsfeed filled up with so much love for these kids. PS can you guess which kid insists on picking their own clothes #theluckyfew #TrigPaxson #T21.”