Heidi Klum posts baby picture of herself being breastfed to mark 51st birthday... as she celebrates with her children and husband Tom Kaulitz, 34

Heidi Klum marked her 51st birthday in style on social media, posting a heartwarming throwback on her Instagram page.

Her photo showed little Heidi as an infant in 1970s West Germany, being breastfed by her doppelganger mother Erna Klum. 

For background music, Heidi selected the 1976 Stevie Wonder song Isn't She Lovely, which he wrote in honor of the birth of his own daughter Aisha Morris.

She also revealed on Instagram that day that she was treated to a family picnic for her big day, surrounded by festive pink balloons including two that read '51.'

The world-famous supermodel was joined by her husband Tom Kaulitz, 34, as well as her children Leni, 20, Henry, 18, Johan, 17, and Lou, 14.

Heidi Klum marked her 51st birthday in style on social media, posting a heartwarming throwback of herself being breastfed by her mother Erna Klum

Heidi Klum marked her 51st birthday in style on social media, posting a heartwarming throwback of herself being breastfed by her mother Erna Klum

Heidi and Erna pictured

Heidi and Erna pictured

Heidi had her three younger children with her ex-husband Seal, who also adopted Leni, the product of Heidi's dalliance with Italian businessman Flavio Briatore. 

Posting a sweet picture of her loved ones gathered around the table for her alfresco birthday lunch, Heidi wrote: 'All I could wish for.'

She also uploaded a joyful snapshot of herself and Tom, the guitarist for the German band Tokio Hotel, sharing a romantic kiss while toasting each other.

Heidi was also treated to social media tributes from her celebrity friends, including Paris Hilton, who posted an Insta Stories snap of the two of them dancing.

Sofia Vergara, who is Heidi's fellow judge on America's Got Talent and also a close gal pal, effusively expressed her affection for the birthday girl on Instagram.

'Feliz cumpleaños to the most fun and beautifull girl in the world!!!!' wrote the Modern Family bombshell, alongside a picture of herself kissing Heidi's shoulder on America's Got Talent. 'Luv so much @heidiklum.'

Heidi has taken a good-humored approach to aging, joking recently: 'The good thing is that my eyesight is getting worse and I can't see everything so clearly anymore.'

More sincerely, she explained the way she copes with getting older: 'I just accept it – there's nothing you can do about it anyway. Why overthink it? It is what it is.'

The world-famous supermodel was joined by her husband Tom Kaulitz , 34, as well as her children Leni, 20, Henry, 18, Johan, 17, and Lou, 14

The world-famous supermodel was joined by her husband Tom Kaulitz , 34, as well as her children Leni, 20, Henry, 18, Johan, 17, and Lou, 14

She also uploaded a joyful snapshot of herself and Tom, the guitarist for the German band Tokio Hotel, sharing a romantic kiss while toasting each other

She also uploaded a joyful snapshot of herself and Tom, the guitarist for the German band Tokio Hotel, sharing a romantic kiss while toasting each other 

Heidi was also treated to social media tributes from her celebrity friends, including Paris Hilton, who posted an Insta Stories snap of the two of them dancing

Heidi was also treated to social media tributes from her celebrity friends, including Paris Hilton, who posted an Insta Stories snap of the two of them dancing

Sofia Vergara, who is Heidi's fellow judge on America's Got Talent and also a close gal pal, effusively expressed her affection for the birthday girl on Instagram

Sofia Vergara, who is Heidi's fellow judge on America's Got Talent and also a close gal pal, effusively expressed her affection for the birthday girl on Instagram

Heidi's age has drawn particular scrutiny because her husband, who like her hails from Germany, is a quarter-century younger than she is. 

'I'm 50 and no longer 20. I'm not a young girl who hasn't experienced anything yet or has no idea about life,' she acknowledged to Glamour UK last year.

'Time won't stand still for me and Tom will never catch up with me. I'll always be 16 years older, and I'm aware of that,' Heidi continued.

'I know that I will look older than him sooner. Maybe it will be a problem for me in ten years' time, maybe he won't like it then,' she reflected.

'In 20 years, I'll be 70. I usually plan for the future – but with my husband, I live in the here and now,' the Teutonic blonde shared.