Outnumbered. I think that’s how my youngest daughter feels.

Before her sister left for university, it was equal: two parents, two children. If she needed someone to back her up in a family argument or someone to help persuade us to allow her to do something, she knew who to call upon for support.

Now she’s on her own. “I’m not going anywhere with you two,” she will say. “I wouldn’t be seen out with you,”, “I’m not watching TV with you.”

She doesn’t like living with us. It isn’t only the dynamics in the house that are leaving her bereft. Ordinarily, if she wanted someone to go shopping with, or simply someone to chat to, she had a ready-made companion. Now she’s got no-one on tap, and the void it has left in her life is clear to see.

Of course, she would never, ever, admit it, but she misses her older sibling. When her sister is home she is brighter and more cheerful all round.

Their relationship wasn’t by any means perfect. They argued fiercely over many things, but essentially they were pals. Many a night they would sit in one or the other’s room watching something highly inappropriate on the laptop or laughing at something on Facebook.

But now my daughter rarely surfaces from her room, retreating there as soon as she has eaten. And even eating with us, I can see, she finds distasteful. If I allowed her to eat upstairs, we would not see her at all.

I offered to take her shopping in half-term, on a day trip somewhere special, but she didn’t seem interested. “What is there to do, except for shop?” she said, which surprised me a bit, coming from someone whose main pleasure appears to be filling her wardrobe.

Empty nest syndrome is usually associated with parents, and we too miss my eldest daughter. I miss the increased comings and goings of friends to the house, and the - however occasional - family days out. I even miss the arguments and the demands made by my eldest daughter who, when home, is far less self-sufficient than her sister. It brought a bit more life to our home.

But no-one seems to consider how a sibling’s departure affects brothers and sisters.

Having said that, I don’t think I was missed by my brother and sister when I went away to study all those years ago. Having been forced to share a room, my sister suddenly had one all to herself and loved it. My brother didn’t even notice I’d gone.

I don’t think my parents missed me either. I think they were keen to get rid of us: as soon as we left they revamped the whole house and turned it into a B&B.