Novel X and Novel Y are both semiautobiographical novels and contain many very similar themes and situations, which might lead one to suspect plagiarism on the part of one of the authors
However, it is more likely that the similarity of themes and situations in the two novels is merely coincidental, since both authors are from very similar backgrounds and have led similar lives
If the authors of Novel X and Novel Y are from very similar backgrounds and have led similar lives, suspicions that either of the authors plagiarized are very likely to be unwarranted.