Father’s Day seems to be a sore subject for some people. Take actor Oliver Hudson for example, who slammed his estranged biological father Bill Hudson in an Instagram post Sunday.

The 38-year-old actor shared a childhood photo of himself and his sister Kate Hudson with their father, and he wasn’t subtle with the caption: “Happy abandonment day… @katehudson.” Ouch.

Happy abandonment day… @katehudson

A photo posted by Oliver Hudson (@theoliverhudson) on Jun 21, 2015 at 6:18pm PDT

Heavy, right? But it’s hardly the first time Oliver or Kate have spoken out about their biological father. The siblings have both gone on record to say that they consider their mother Goldie Hawn’s longtime partner Kurt Russell to be their real father.

“[Bill Hudson] doesn’t know me from a hole in the wall. But I don’t care. I have a dad [Russell]. The bottom line is, you call your kids on their f–king birthday. I’m glad I had a dad who was there on my birthday,” Kate told Vanity Fair back in 2000.

Meanwhile, Bill Hudson had his say when he released his tell-all book, 2 Versions: The Other Side of Fame and Family in 2011, in which he also said some unkind things about his children.

“I love Kate, but … She has done stuff which is just awful. She is a spoiled brat in my eyes and at the end of the day, she should meet her little sister. I should meet my grandchild and she should help her grandmother,” he wrote.

Meanwhile this Father’s Day, the actress made no mention of her biological father, she only celebrated Russell with a sweet photo on Instagram that she captioned, “Pa, just simply….. Thank you Happy Fathers Day I love you to the moon and back. ✨ #HappyFathersDay”

Pa, just simply….. Thank you Happy Fathers Day I love you to the moon and back. ✨ #HappyFathersDay

A photo posted by Kate Hudson (@katehudson) on Jun 21, 2015 at 9:40am PDT

The Huffington Post has reached out to Bill Hudson for comment.

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