Most parents of teenagers report that their off-spring leave dirty dishes under the bed amongst grubby post-party clobber.
But Damien and Mary Douglas, from Lucan in south Dublin, have no such problems with their 18-year-old, identical twin daughters. In fact, they would be delighted if Una and Ailis could be wayward in some small way; but the fact exists that since they can do nothing at all for themselves, they will never be grounded or sent to their rooms for bad behaviour.
The reason being that the girls suffer from a rare chromosomal disorder called Wolf-Hirschhorn syndrome (WHS); so rare in fact that their father Damien believed, until recently, that his girls were the only twins in the world with this condition. He has since discovered that there is a set of twins in South Africa similarly affected.
The Douglas's had no idea they would be walking a very different road to the one they envisioned when Mary was admitted to hospital in May 1995 to give birth to the last two of their five children.
Initially, the girls seemed like any other babies, but over time it emerged they were poor feeders, they vomited frequently and they remained floppy. At 12 weeks, their parents learned that the twins were severely handicapped.
Damien says the diagnosis was a terrible blow. "I hadn't expected it; the world fell out from under me. But there was also a sense of relief that there was an explanation for what had been happening."
Una and Ailis have many symptoms typical of WHS; they suffer from epilepsy, poor muscle control, problematic joints, developmental delays, they can't sit, walk, speak or comprehend what is going on. They are also incontinent and are fed through tubes in their stomachs.
A typical day involves getting the girls up, showered, put in nappies, dressed and ready to begin the various sensory experiences that the family provides.
Damien says their three other children, Fergal, 24, Ciara, 22, and Orla, 21, are very much part of the team that works with the girls when their schedule allows.
Activities include physiotherapy, music, mirror-work and walks in the fresh air.
The girls go to bed at about 9pm when they will be pump-fed during the course of the night. It's a punishing routine, yet Damien doesn't waver in his devotion.
So much so he felt he had to take early retirement from the HSE earlier this year, because he feared budget constraints would cut off services to his daughters. Fortunately, his worst fears haven't been realised – yet.
He says while he has had nothing but full support from individual HSE staff members, budget cuts have thrown services into disarray.
"It's those supports (from day centres to vital equipment in the home) that allows you to go on doing what you do. Without them, the whole thing would collapse."
In the meantime, Damien and Mary continue to devote themselves to Una and Ailis.
"These are our girls and we love them to bits. It's been difficult at times but it's been beautiful at times too. They both have gorgeous smiles and their giggles would gladden your heart."