Back in the 1970s the family at the core of The Brady Bunch television series seemed something of an anomaly.
The theme song explains it all:
Here's the story Of a lovely lady Who was bringing up three very lovely girls ... Here's the story Of a man named Brady Who was living with three boys of his own ... Until one day when this lady met this fella And they knew that it was more than just a hunch That this group must somehow form a fam'ly And that's how we became the Brady Bunch.
This may have been one of television's first blended families, but according to Nigel Latta, psychologist and author of The Modern Family Survival Guide, step-parenting is nothing new.
"We've raised children in blended families throughout the entire human history," says Latta.
"It used to be back in the day your dad would get sat on by a mammoth so you would move in to the cave next door ... it's a very normal way of raising children."
Good Therapywebsite says: "Households in which two married people are the parents of all the children in the home are now the exception in the United States. Divorce affects more marriages than not, and step-families or 'blended families' are nearly as common."
Blended families are on the rise here too and the issues associated with them are well documented.
Kiwi Families, a website for "passionate parents", lists some potential problems including: accusations from children that "You're not my Mum/Dad!", parents taking their own child's side in a dispute, jealousy (not just between step-siblings but also an adult's jealousy of their partner's children) and the (sometimes complicated ) relationship that may exist with the step-children's "other" parent.
With such tricky minefields to negotiate, you'd wonder where anyone finds the courage to enter such an arrangement. Yet the bottom line is that few people are likely to set themselves the goal of being part of a blended family with its attendant possibility of multi-faceted conflicts. It is life's challenges - such as solo parenting, relationship break-ups, divorce and death of a partner or spouse - that often act as an initiating factor in creating such combined family units.
By all accounts, being a stepparent can be difficult. In fiction at least, they're not often portrayed in a positive light. A wicked stepmother has been a well used character through the ages. TV Tropes says: "the woman hostile to her stepchildren ... is a perennial trope ... She generally favors her own children - whether from a previous marriage or this one - over her stepchildren."
As for stepfathers, a Huffington Post writer reckons they can fly under the radar and are often unacknowledged: "Stepfathers seem to be mysterious. They are often referred to as removed and distant."
Fortunately there's a plethora of advice for budding stepparents. Barnados says: "Involve yourself in the children's lives slowly", "Understand and accept that the children are likely to feel loyal towards their natural parents" and "Make sure children have time alone with their natural parent". Less positively, Barnados goes on to say: "Be patient, lower your expectations" and "It may be helpful to remember that you may not love or even like your step-children right away".
The children, perhaps already jaded and confused about developments surrounding them, often have good reasons for being wary of a new stepparent. Good Therapy says: "Children of blended families may struggle with issues such as jealousy, confusion, animosity, resentment, rivalry, loyalty and loss. They may still be trying to sort out the pain and grief over the loss of the family they had."
While the adults in a blended family have opted into the new situation, the children - who have presumably had little say in the matter and may well be suffering the after-effects of emotional upheaval - are simply expected to slot neatly into some new blended family unit with a minimum of fuss.
Unsurprisingly, there's evidence that such transitions are not always declared an unqualified success. According to the Ministry of Social Development, a child's experience of blended families is likely to be of short duration: "For nearly half, the spell ends in five years. Children in blended families, especially girls aged 10 - 16 and in families with step-fathers, tend to leave home at an earlier age than children in other family circumstances. Many families adapt successfully to change, but there can also be levels of poverty, tension, instability and insecurity that put children and young people at risk."
The Brady Bunch - aided by its cosy storylines centred on camping trips, orthodontic braces, school plays, secret admirers, slumber parties and their wisecracking housekeeper, Alice - may have made it all seem positive and effortless, but in reality it's little wonder children in embryonic blended families can feel uncomfortable and uncertain about the new arrangements.