(one's) (own) flesh and blood

One's family member(s). You're my own flesh and blood—how you could you steal my idea? She's our flesh and blood, so let's all try to get along with her while she's in town. I know you don't want to believe that your own brother, your flesh and blood, is capable of betraying you like this, but the evidence against him is pretty damning.

be only flesh and blood

1. To have human flaws and thus be imperfect. I know you idolize me, but I'm only flesh and blood, just like you—I make mistakes too! I don't condone him for giving in to temptation, but I don't blame him, either. Like any of us, he's only flesh and blood. Your little sister really looks up to you. To her, you're not only flesh and blood, you're a hero.

2. To be unable to do things that are beyond the means of a mortal human. I don't know how the boss thinks we can get all this work done before the Christmas deadline. We're only flesh and blood! Right, like I have any control over the weather. I'm only flesh and blood, you know. Come on, I'm only flesh and blood—there's no way I can get this house cleaned up in an hour!

flesh and blood

1. The human body (and the limitations thereof). We need to get a crane to move this slab—it's too heavy for mere flesh and blood to handle. I saw some horrifying things as a medic in the war. Flesh and blood are not meant to sustain those kinds of wounds. I'm sure the gods didn't get sick—that's an affliction unique to flesh and blood.

2. Describing an actual, living person. It's hard to think of these relatives that I've never met as flesh and blood people. Just because you can't see these people you attack online, that doesn't mean they're not flesh and blood. These characters feel so much like flesh and blood that it's hard to remember they're not real.

3. One's relative(s). In this usage, "own" can be used before "flesh." You're my own flesh and blood—how could you spill my secrets to the tabloids? She's our flesh and blood, so let's all try to get along with her while she's in town. How could someone who's my own flesh and blood just steal my idea like that?

4. An entity possessing life-like qualities. A skilled writer can take wooden characters and turn them into flesh and blood. I'm sorry, but these characters don't feel like flesh and blood to me. I just can't see real people acting they way they do. Wow, how did you manage to write a ghost like flesh and blood?

5. Human, and therefore flawed and imperfect. I know you idolize me, but I'm flesh and blood, just like you—I make mistakes too. I don't condone him for giving in to temptation, but I don't blame him, either. Like any of us, he's only flesh and blood. Your little sister really looks up to you. To her, you're not flesh and blood, you're a hero.

flesh and blood, I'm only/one's own

I’m only human; members of my family. The pairing of flesh and blood dates back very far. In English it appears in the Bible (Matthew 16:17; Ephesians 6:12), Shakespeare’s Julius Caesar (3.1: “and men are flesh and blood, and apprehensive”), and numerous other writings, mostly in the meaning of being only human (Thomas Hood, “The Song of the Shirt”: “Oh God! that bread should be so dear and flesh and blood so cheap!”). The other sense, of blood relations, appeared in a 1300 manuscript (“He . . . es your aun fless and blod”), and numerous other early sources, as well as in Shakespeare’s The Merchant of Venice (where Gobbo says to his son, “If thou be Launcelot, thou art mine own flesh and blood,” 2.2).