"I am the son of my parents."
Translation:Soy el hijo de mis padres.
In spanish there are 2 different verbs that can be translated as "to be": "ESTAR" and "SER".
To address condition, use "estar" (estoy/estás/está/estamos/estáis/están)
Ex: La manzana está verde / the apple is green = unripe.
To address an essential quality, use "ser" (soy/eres/es/somos/sois/son)
Ex: La manzana es verde / the apple is green = color green, which is an essential characteristic.
This (permanent vs. temporary) was how it was explained to me by a native speaker. If something is red, for instance, it is always red. If you are someone's son or daughter, it is and will always be true. But if you are happy or sad that is a state of being at that specific moment. There are other specific rules (from Spanish class that I learned), however, this is basically the easiest way to decipher when unsure which should be utilized.
Because it doesn't convey possession. That sentence would mean "I'm my parents son," not "I'm my parents' son" with the apostrophe. To convey possession in Spanish, you always use "de" plus whoever is claiming ownership of the object (i.e., you say "of my parents" instead of "my parents' ").