Twin helps sister to walk, talk and play

But the four-year-olds share more than most.

Felicity has cerebral palsy but has learned to cope with the difficulties thrown at her thanks to her sister – who she has copied to learn how to walk, talk and play.

The twins' proud mum and dad, Gary, aged 28, and Hayley, 27, from Walsall believe that it's thanks to the girls' special bond that Felicity has developed so well.

Hayley said: "We're so proud of our girls. Felicity has been able to watch her sister reach lots of milestones, and through copying has been able to reach them, too.

"Tiffany has shown her sister how to roll over and sit up, and even walk. When Felicity began to speak, she was saying words that she'd heard her sister say. Even now, as the girls learn to read, Tiffany will help Felicity sound out words."

The couple first noticed Tiffany's huge influence on her twin sister when the girls were learning to walk.

Hayley said: "We were starting to worry as Felicity had got to 18 months old and she still wasn't walking – the cerebral palsy has really affected her right leg so it was a concern.

"A physiotherapist came to the house to try and teach her some exercises to help her walk, but she just wasn't getting it. But then all of a sudden Tiffany stood up next to Felicity and showed her what to do. Felicity copied her sister immediately, and before we knew it she had learned to walk."

She added: "It was amazing – even the therapists agree that watching and copying her sister has had a huge impact on her. We'd already started to wonder if Felicity was looking to Tiffany to teach her things, but this proved it for us."

Since then, Felicity has continued to copy her sister, and has continued to progress well. Hayley said: "Felicity is a little behind other children her age, but copying her sister has helped her develop.

"Felicity used to be nervous about walking on grass –as she was a little unstable already with her leg she didn't really like it, but Tiffany would hold her hand and show her what to do, and now she's fine with it.

"Felicity has learned how to use felt tips and do jigsaws because Tiffany does them all the time, and will show her how they work. Even when they were learning to talk, Felicity would repeat her sister. Tiffany would ask us for a drink, and then before we knew it so would Felicity – it's really been incredible."

The twins were born two and a half months early in February 2010.

The girls' dad, Gary, said: "After initial breathing problems, Tiffany was doing really well, whilst Felicity developed a very serious bowel condition called neonatal necrotising enterocolitis – her bowel had started to die and it was spreading to her other intestines. We didn't know if she was going to make it, but luckily they were able to operate and save her life.

"After the operation they gave Felicity a brain scan and they noticed she had dark spots on her white brain matter.

"We had no idea what this meant but the doctors explained she'd developed periventricular leukomalacia – a form of brain damage that can lead to cerebral palsy. We think she may have developed it due to the stress and trauma of her birth and operations but we'll never know 100 per cent.

"It was horrible to learn that Felicity had this, but each day she slowly got better, and six months later she was finally discharged. It was a huge relief."

Gary now aims to compete in the London Marathon next year in aid of Birmingham Children's hospital.

To help him fundraise, visit uk.virginmoneygiving.com and search for Gary Williams.