The Big Bang Theory: What's in Howard's Father's Letter
Howard's father's letters are one of the Big Bang Theory's mysteries, left unanswered from season 6 to the finale. Howard's letter may have said so.

What exactly was in the 18th birthday letter Howard's father received on The Big Bang Theory? Over the years, audiences have met members of the Pasadena gang's family, but Howard's family remains one of the most mysterious and intriguing. Much has been said about his close relationship with his mother, Debbie Wolowitz (Carol Ann Susie). Although she never appeared on screen, she appeared steadily in the series until her death. However, Howard's estranged father, Sam Wolowitz, is pretty much non-existent on the sitcom.
Even after The Big Bang Theory ended, the identity of Howard's father remained a mystery. Many thought the series would address this issue by the end of the show; however, little attention was paid to the supporting cast throughout the final season. Instead, the biggest arc is Sheldon's (Jim Parsons) and Amy's (Mayim Bialik) Nobel Prize bid, with Penny (Kelly Cuoco) and Leonard (John Ni Galecki) had opposing views on having children intertwined. In between it all, The Big Bang Theory left some big questions about Howard's relationship with his father. This includes the contents of a letter written by Howard's father for Howard's 18th birthday - a After TBBT season 6. Here's what might be included in Howard's father's letter.
What The Show Revealed About Howard's Dad Before The Letter

Sam Wolowitz, Howard Wolowitz's father, is mentioned several times during the 12 years of The Big Bang Theory. The first mention dates back to season 3's "Precious Pieces," which revealed that Sam abandoned Howard's first family when he was 11, though his reasons for doing so are unclear. This leads to season 6's "Closet Reconfiguration," in which Sheldon discovers a letter Sam sent to Howard before the events of The Big Bang Theory began, but Howard refuses to read it and eventually burns it. And then the whole episode revolves around whether Sheldon - who is the only one who actually reads the letter - will tell everyone. He does end up describing Howard's father's letter off-screen, which sets up the dramatic scene that reveals the letter's likely contents.
The Whole Gang Provided Guesswork Around The Letter

In the end, the gang helps Howard make a decision, suggesting that each reveal different possibilities of what Howard's father's letter might contain, and Howard can choose what he believes to be true. Raj (Kunal Nayyar) describes a traditional birthday card that reads, "Happy birthday, Howard. Love you, Dad." Sheldon basically Stealing the Goonies story, telling Howard the birthday letter is a map to one-eyed Willie's treasure, Amy claims Howard's dad was in the auditorium when he graduated from high school. Penny said the letter explained why Sam left, which allowed him to live a different life, while Leonard addressed his father's reminder that family is everything and shouldn't be abandoned like he was. Finally, Bernadette (Melissa Rauch) said that inside was a photo of Howard just born, with a note on the back that said: "Howard, my son, my greatest Gift."
Only one of the choices is true, and given how little information is known about Howard's father, it's hard to tell which one it is - though it's safe to say that Sheldon's father is pretty much a lie. The belated introduction of Josh (Matt Bennett), Howard Wolowitz in The Big Bang Theory is believed to be the half-brother who was an oceanography student in San Diego, however, reveals that Sam had a relationship with the second The family lives together. What's unclear is whether he's still with them, or if he's left them too. Most likely the latter, considering otherwise it would be an opportunity Howard was reunited with his father -- a possibility that hadn't even been mooted. As dramatic as this scene is, it seems most plausible for Penny to think that Sam started a different life. This doesn't give any hope of Sam coming back, but rather an explanation of why he left, it shuts Howard up. Regardless, if CBS is still preparing for another Big Bang Theory spinoff, Howard Jr. may come forward, and viewers will discover the true content of Howard's father's letter.
Why It Doesn't Matter What Was In Howard's Letter

In the end, the contents of Howard's father's letters don't matter in the long run. Nothing would be enough to make up for his previous abandonment, and nothing could counteract the combined emotions of all his friends' fictional descriptions. In The Big Bang Theory, Howard doesn't have a father figure, but instead has an extended family that supports him. This group of friends cared deeply for him, and they helped him find closure from the letter in a creative way, a current form of affection that far outstripped Howard's absent father. Thus, revealing the contents of the letter would miss the point of the scene: What matters is who is behind Howard, not the sentiments of those who have long abandoned him, so keeping the content mysterious adds depth to Howard's role in The Big Bang Theory and sparks deep and lasting fan discussion.
The Best Theory For Howard's Dad's Letter

The best overall theory about Howard's father's letter is that it contained something everyone was guessing at - except for Sheldon's rendition. That's definitely the healthiest theory out there, and while Howard's father's absence is unforgivable, it's heartwarming to think he was there for graduation, or that he called his son his "greatest gift." To be sure, the birthday card with Raj's "Happy Birthday" proclamation may even contain Penny's thoughts, which is further reinforced by the fact that Sam Wolowitz did move and start a new family. Either way, The Big Bang Theory fans will never really know what the contents of Howard's father's letter are, and it's only up to the imagination.