The characters in this story are all over eighteen and the age of consent, sex if it happens is consensual. UK English is the rule if the spellings Mum or colour annoy you, don't go any further, for the rest enjoy.
*****
Jack and Chloe snuggled up on Chloe's bed. Chloe languidly stroked Jack's dick, as he lightly caressed her breast.
"Jack, this is really nice, but do you want to go further?"
"Travelwise or what?"
"No silly, do you want to actually make love, I mean it's been so nice just being naked and touching each other, but I sometimes wonder what it would be like to actually go the whole way."
"Oh! really, well yes I've thought about it, but, well, it's a big step from just being happy nudes and helping each other out to being lovers."
"Would we be lovers or would it just be sex?"
"You mean a lust not love kind of thing?"
"Pretty much! what do you think?"
"Little Sis, I can't just poke you and then walk away when we get back, it's not something I'd be comfortable with, how about you."
"Jack I love you so much, and I think it's more than just because your my cool older brother, but, I have so little experience I really don't know."
"Well in that case, we can't go any further, it's like any relationship, until your sure don't do it, okay?"
"OK, if you're sure and it's not something that's going to come back and bite us."
" Chlo, what's more likely to bite us is to leap on one another and then find out it's only lust, that could destroy us and M & D."
"Yea you're right, cool, mmmm, shall we go to the beach or just lie here?"
"Beach, but let's just lay back, I'll stop teasing you if you stop teasing me, when we calm down, we dress and go down to the beach."
"OK big bro."
They lay together but moved their hands from intimate contact, the warm sun bathed the room and they drifted off to sleep.
"Ahem, I assume you have a reasonable explanation for the fact the pair of you are naked in bed together?" The familiar voice was just feet from the bed.
"Jack! Chloe! what the hell's going on?" said another familiar female voice.
"Mmmum? Dad?" Chloe opened an eye then both, then sat up and shook Jack.
"Jack! oh boy! I think you need to wake up, you are not going to believe who's here."
Jack opened his eyes and gazed across the bed, smiling he waved a hand, "Hi Mum, Hi Dad, when did you get here?"
"Just now, but will you kindly explain why you're both bare arse naked in bed together?" Dave Ashton glared at his son, trying hard not to look at his daughter, he half turned to his wife, "Rose can you take your eyes off his dick please?"
"Dave, I'm just admiring my two beautiful children, wow, have they grown up!" Rose Ashton exclaimed then reddened as Jack's dick twitched and began to stiffen.
"Ooops sorry Ma," Jack said trying to cover himself.
Chloe took the opposite course of action and untangling herself from Jack stood up in front of her father and mother.
"It's so lovely to see you, are you staying, if so come to the beach, we've met a terrific Spanish family, they'll really enjoy meeting you." she smiled sweetly then popped a kiss on each of her parents cheeks.
"Cut that out young lady and cover yourself up, I shouldn't be able to see you like this, much less should you be seen like it by your brother, now what is going on?" Dave actually stamped his foot, which made the others laugh. Feeling stupid he began to laugh too.
"Alright, calm down, but please tell us what's going on, are you two sleeping together, come on?"
"Dad," said Jack sitting up and looking at his parents, "I'm not going to lie about this, yes we've slept together, but no we're not, errr, sleeping together, as in sexually active, ok?"
"OK, well yes and no, I mean why do you need to sleep together, it's hot out here and I would have thought you'd want some space and stuff." Dave trailed off and looked at Rose, whose amused expression ruffled him. "This is pretty serious you know."